Unveiling the bosonic nature of an ultrashort few-electron pulse

TL;DR

This paper demonstrates that ultrashort few-electron pulses in quasi-one-dimensional conductors exhibit bosonic plasmon excitations, with tunable velocities, providing a new way to study fractionalization in low-dimensional quantum systems.

Contribution

It provides the first time-of-flight measurements showing the bosonic nature of electron pulses in a tunable quasi-one-dimensional system, bridging the gap between theory and experiment.

Findings

Plasmon velocity can be tuned over an order of magnitude.

Quantitative agreement with a parameter-free theoretical model.

Direct observation of fractionalization phenomena in real-time.

Abstract

Quantum dynamics is very sensitive to dimensionality. While two-dimensional electronic systems form Fermi liquids, one-dimensional systems -- Tomonaga-Luttinger liquids -- are described by purely bosonic excitations, even though they are initially made of fermions. With the advent of coherent single-electron sources, the quantum dynamics of such a liquid is now accessible at the single-electron level. Here, we report on time-of-flight measurements of ultrashort few-electron charge pulses injected into a quasi one-dimensional quantum conductor. By changing the confinement potential we can tune the system from the one-dimensional Tomonaga-Luttinger liquid limit to the multi-channel Fermi liquid and show that the plasmon velocity can be varied over almost an order of magnitude. These results are in quantitative agreement with a parameter-free theory and demonstrate a powerful new probe for directly investigating real-time dynamics of fractionalisation phenomena in low-dimensional conductors.